Windows下的dll

Question

我需要从托管C ++代码动态加载.dll。 下面的代码执行此操作

[DllImport("kernel32.dll", SetLastError = true,
        CharSet = CharSet::Unicode, ExactSpelling = true,
        CallingConvention = CallingConvention::StdCall)]
    static HMODULE LoadLibrary(LPCTSTR lpFileName);

    [DllImport("kernel32.dll", SetLastError = true,
        CharSet = CharSet::Unicode, ExactSpelling = true,
        CallingConvention = CallingConvention::StdCall)]
    static BOOL FreeLibrary(HMODULE hModule);

    [DllImport("kernel32.dll", SetLastError = true,
        CharSet = CharSet::Unicode, ExactSpelling = true,
        CallingConvention = CallingConvention::StdCall)]
    static FARPROC GetProcAddress(HMODULE hModule, LPCSTR lpProcName);

    typedef int (*CFunction)();

    int _tmain()
    {
        HMODULE pLib = LoadLibrary(TEXT("FunctionDLL.dll"));
        if(pLib != 0)
        {
            FARPROC function = GetProcAddress(pLib, "QFunction");
            if (function != 0)
                MessageBox::Show(Convert::ToString(function()));

            FreeLibrary(pLib);
        }
        else
        {
            MessageBox::Show(L"Error", L"Couldn't load ell");
            Close();
        }

        return 0;
    }

但是函数始终为null。 我认为dll我们错了。 下面的dll代码：

.h文件

#ifdef __FUNCTIONDLL__
#define __FUNCTIONDLL__

#ifdef FUNCTIONDLL_EXPORTS
    #define FUNCTIONDLL_API __declspec(dllexport)
#else
    #define FUNCTIONDLL_API __declspec(dllimport)
#endif

#ifdef __cplusplus
extern "C"
{
#endif

FUNCTIONDLL_API int QFunction();

#ifdef __cplusplus
}
#endif // __cplusplus

#endif // __FUNCTIONDLL__

.cpp文件

#include "FunctionDLL.h"

int QFunction()
{
    return 42;
}

Answer 1

您的c ++项目中是否有一个.def？ 如果不只是添加一个.def

LIBRARY   FunctionDLL
EXPORTS
  QFunction   @1